Fix an error in a keyed lookup stub - HeapNumbers treated as strings.

Review URL: http://codereview.chromium.org/155924

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@2527 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ia32/ic-ia32.cc

@@ -43,6 +43,10 @@ namespace internal {
 
 
 // Helper function used to load a property from a dictionary backing storage.
+// This function may return false negatives, so miss_label
+// must always call a backup property load that is complete.
+// This function is safe to call if the receiver has fast properties,
+// or if name is not a symbol, and will jump to the miss_label in that case.
 static void GenerateDictionaryLoad(MacroAssembler* masm, Label* miss_label,
                                    Register r0, Register r1, Register r2,
                                    Register name) {
@@ -56,7 +60,7 @@ static void GenerateDictionaryLoad(MacroAssembler* masm, Label* miss_label,
   //
   // r2   - used to hold the capacity of the property dictionary.
   //
-  // name - holds the name of the property and is unchanges.
+  // name - holds the name of the property and is unchanged.
 
   Label done;
 
@@ -274,13 +278,20 @@ void KeyedLoadIC::GenerateGeneric(MacroAssembler* masm) {
   __ bind(&slow);
   __ IncrementCounter(&Counters::keyed_load_generic_slow, 1);
   KeyedLoadIC::Generate(masm, ExternalReference(Runtime::kKeyedGetProperty));
-  // Check if the key is a symbol that is not an array index.
+
   __ bind(&check_string);
+  // The key is not a smi.
+  // Is it a string?
+  __ CmpObjectType(eax, FIRST_NONSTRING_TYPE, edx);
+  __ j(above_equal, &slow);
+  // Is the string an array index, with cached numeric value?
   __ mov(ebx, FieldOperand(eax, String::kLengthOffset));
   __ test(ebx, Immediate(String::kIsArrayIndexMask));
   __ j(not_zero, &index_string, not_taken);
-  __ mov(ebx, FieldOperand(eax, HeapObject::kMapOffset));
-  __ movzx_b(ebx, FieldOperand(ebx, Map::kInstanceTypeOffset));
+
+  // If the string is a symbol, do a quick inline probe of the receiver's
+  // dictionary, if it exists.
+  __ movzx_b(ebx, FieldOperand(exd, Map::kInstanceTypeOffset));
   __ test(ebx, Immediate(kIsSymbolMask));
   __ j(zero, &slow, not_taken);
   // Probe the dictionary leaving result in ecx.

test/mjsunit/regress/regress-155924.js

+// Copyright 2009 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// A HeapNumber with certain bits in the mantissa of the floating point
+// value should not be able to masquerade as a string in a keyed lookup
+// inline cache stub.  See http://codereview.chromium.org/155924.
+
+A = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ];
+
+function foo() {
+  x = 1 << 26;
+  x = x * x;
+  // The following floating-point heap number has a second word similar
+  // to that of the string "5":
+  // 2^52 + index << cached_index_shift + cached_index_tag
+  x = x + (5 << 2) + (1 << 1);
+  return A[x];
+}
+
+assertEquals(undefined, foo(), "First lookup A[bad_float]");
+assertEquals(undefined, foo(), "Second lookup A[bad_float]");
+assertEquals(undefined, foo(), "Third lookup A[bad_float]");